Re: Extensive article on Rivendell and Grant Petersen

On Wed, 25 Sep 2024 09:05:25 GMT, Roger Merriman <roger@sarlet.com>
wrote:
 

Frank Krygowski <frkrygow@sbcglobal.net> wrote:

On 9/24/2024 3:17 PM, Catrike Ryder wrote:

On Tue, 24 Sep 2024 14:14:41 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:
>

You might do well to read some of the archives of this group. There have
always been people posting opinions that were factually wrong, and there
have always been people pointing out those mistakes. As I've noted
earlier, having mistakes pointed out is a necessary part of the process
of education.

>
That's fine of the person being corrected understands that the
corrector is qualified to do so and is truly interested in making
things better. In my opinion, you fall far short of both those
standards.

>
Your opinion on that matter is worthless. You don't have anywhere near
the background needed to judge technical proficiency. Professional
Engineering licensing boards of two different states have disagreed with
you, not to mention those conferring my engineering degrees and those
institutions for whom I've worked.
>

There are many examples of ideas that were posted frequently, and noted
as wrong. Most of them seldom pop up any more - and not only, I think,
just because there are fewer posts. I think people actually learned things.
>
Examples of mistaken claims? Chains wear by stretching the metal. Old
frames get "soft." Increasing spoke tension makes a wheel more rigid.
Tying and soldering spokes makes a wheel stronger. Headsets fail by true
brinelling due to impact loads. Hanging a bike by the front wheel makes
the spokes stretch... and many more.
>
BTW, what was that stopping distance from 20 mph again?  ;-)

>
20 MPH would be maybe 9/10 feet if I didn't concern myself with
slamming the chain rings into the ground or doing a face plant on the
ground in front of the bike. 30 MPH would be a little further. Two
front brakes work better than one, especially when the rider's weight
is already more over the front wheels before he applies the brakes.

>
Right, good one. There is no way you can stop your tricycle in 10 feet
from 20 miles per hour. That would require a deceleration of 43 ft/s^2
or 1.34 times the acceleration of gravity. IOW you'd need tires with a
static coefficient of friction at least 1.34, plus absolutely perfect
application of both brakes so that both wheels were at the absolute
limit of traction but not skidding. And you'd have to be in a "nose
wheelie" all the while, with your rear tire up in the air so every bit
of your weight was on the front wheels. It's essentially impossible.
>
For 9 feet, your acceleration would have to be nearly 48 ft/s^2, and
besides absolutely perfect braking reflexes, you'd need tires with a
static coefficient of friction at least 1.48.
>
And 30 mph would be _much_ farther, not "a little." The velocity term
gets squared in the relevant calculation, much as it does when
calculating kinetic energy.
>
I'm sure you don't know what a lot of that means. But what you're
claiming is practically impossible. Feel free to prove me wrong by doing
what you claim and posting video evidence.
>
>

Even if he means without thinking time

 Yes, I know I'm going to stop and my fingers are already on the brake
levers.
 

20mph is 6 meters or 20ft for a car,
which almost certainly can out brake the trike.

 I doubt that.
 

If a planned braking action on the MTB probably could reduce that a touch
as it has huge amounts of grip and braking force, and frame allows one to
get behind the rear wheel.
>
Other bikes at best would equal, the old commute bike as it has weight to
the rear is surprisingly effective at emergency stops or just using the
rear brake hard, but even that will during a emergency start to lock the
rear.
>
Neither of the road/gravel bikes would do well at emergency stops as your
in the wrong position ie far too forward.
>
Roger Merriman
>

 A few weeks ago, after posting about braking, I tested the Catrike's
brakes at 15 MPH. I stopped at about 6 feet, keeping the chain rings
off the ground.
--
C'est bon
Soloman